After debuting in Sydney, the treasure hunt kicks off in New York Friday and runs until March 22. Paris (March 23 to 29), London (March 30 to April 5) and Hong Kong (April 6 to 12) will follow.

Interested parties are invited to download augmented reality app Goldrun [iTunes link] to participate. The app will guide users to locations in each city, where Mr Porter shopping bags will appear — via augmented reality — on their phones. Each bag will contain a prize, such as Lanvin sneakers, Paul Smith cufflinks or a pair of A.P.C. jeans.

Mr Porter is also giving away $2,500 gift certificates for one winner and a friend via Facebook.

In addition to the giveaways, the UK-based retailer is also releasing a printed special edition of its weekly journal. There is, of course, a digital tie-in: users can shop from the pages using Mr Porter's Style Help app for iPhones, powered by augmented reality app developer Aurasma.

As an online-only retailer, Mr Porter — and its parent company, Net-a-Porter — are compelled to be more creative when staging offline events. Net-a-Porter has certainly risen to the challenge, staging shopping events and giveaways for Fashion's Night Out and collection launches that required the use of mobile devices at specific locations.

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